1. Field of the Invention
The present invention relates to a traverse drum and a method for manufacturing the same.
2. Prior Art
There have been proposed various grooved traverse drums for automatic winders for winding yarns. The grooved traverse drum are used for surface-driving a take-up package at a high revolving rate and also for traverse a yarn drawn out from a supply package at a high traversing speed. Accordingly, the traverse drum is required to meet various operating conditions. The traverse drum are required to meet the following conditions in respect of function and manufacture.
(i) The traverse drum needs to be an electrically conductive body capable of conducting static electricity generated during the winding operation so that the traverse drum will not be charged.
(ii) The portions to be in contact with a yarn must be abrasion-resistant.
(iii) The traverse drum needs to be capable of breaking ribboning which occurs when the traverse drum and the take-up package are the same in diameter, and needs to be lightweight so that the traverse drum can be stopped instantly upon the occurence of yarn breakage.
(iv) The surface of the traverse drum must have a low coefficient of friction.
(v) Manufacturing processes including a process for forming the complicated grooves must be carried out easily.
(vi) The traverse drum must be stable in accuracy and can be produced at a low manufacturing cost.
As regards Item (i), the surface of some traverse drum is coated, for example with a film of an antistatic agent or a static electricity preventive agent. However such a traverse drum suffers from the abrasion of the film and the abrasion of the body of the drum. As regards Item (ii), metallic pins having a high hardness or ceramic pins are burried in the drum along the yarn passage to prevent abrasion. However such means requires complex manufacturing processes and has problems in respect of quality and cost. As regards Items (iv) and (v), some drum bodies are formed by an aluminum alloy to reduce the weight to 1.5 to 2.0 kg. However, aluminum alloys are inferior in abrasion resistance. In order to improve the abrasion resistance, such a traverse drum is treated to coat the surface with a hard alumite film, however, the hardness of a hard alumite film is, at the most, about 500 Hv and, since an alumite film is nonconductive, the traverse drum is liable to be charged with static electricity.
Accordingly in view of improving the abrasion resistance of the traverse drum, it is desirable to form the traverse drum by a ferroalloy. However, ferroalloys have various drawbacks that the specific weight thereof is 2.6 to 3.1 times that of aluminum alloys the melting point is high, the manufacturing cost of ferroalloys is high and ferroalloys ar hard and less workable than aluminum alloys. Consequently, traverse drum formed by ferroalloys have not widely been used.